End mill grinders



July 23, 1957 H. K.'GUMPHREY 2,799,976

END MILL 4GRINDIRS 3 Sheets-Sheetl l Filed Aug, 5, 1953 July 23, 1957 H. K. GUMPHREY 2,799,976

END MILL GRINDERS Filed Aug. 5, 1953 ls( sheets-sheet 2 July 23, 1957 H. K. GUMPHREY END MILL GRINDERS 3 Sheets-Sheet 3 Filed Aug. 3, 1953 United States iiatent END MILL GRINDERS Harold K. Gumphrey, Plymouth, Wis.

'Application August 3, 1953, Serial No. 371,912

4 Claims. (Cl. 51-101) rlhis invention relates to grinders, and more particularly to a grinder adapted to grind a cutting edge of an end mill cutter, or the like.

It is an object of the present invention to provide a grinder which will grind all cutting edges of an end mill in a single pass of the wheel.

Another object is to provide a grinder which will grind the cutting edges of an end mill more uniformly.

Another object of the invention is to provide a grinder which will grind the cutting edges of an end -mill more rapidly.

A further object is to provide a grinder for an end mill which will reduce the surface temperature resulting from grinding.

A still further object of the invention is to provide a grinder for an end mill, or the like, which may be used in conjunction with the grinding wheel of a common surface grinder.

A still further object is to provide a grinder for an end mill which may be adjusted to accommodate any pitch of cutter.

A still further object is to provide a grinder for an end mill, or the like, which will automatically advance or retard the rotation of the arbor in response to the lead of the cutter.

Still further objects will become apparent upon considering the following specification, which, when taken in conjunction with the accompanying drawings illustrates a preferred form of the invention.

ln the drawings:

Fig. 1 is a top plan view of a grinder made in accordance with the present invention;

Fig. 2 is a side elevational view of the grinder shown in Fig. l, parts thereof being broken away to more clearly illustrate certain other parts;

Fig. 3 is a transverse cross-section taken on the line 3-3 of Fig. 2, looking in the direction of the arrows;

Fig. 4 is an end elevational view of the grinder as seen from the left in Fig. l;

Fig. 5 is an end elevational view of the grinder as seen from the right in Fig. 2, and showing the relation between a two blade cutter and a grinding wheel; and

Fig. 6 is a cross-section taken on the line 6-6 of Fig. 2, looking in the direction of the arrows.

Referring to the drawings, and particularly to Fig. 2, the end mill grinder is built on a base 10, which has a dove-tailed groove 11 (Fig. 3) therein. The groove 11 receives a tongue 13 of a sliding table 15. The table 15 is composed of a lower section 15 slidable on the base 10 and an upper part 15" joined to the lower portion by hinges ifi-17 and slidable therewith. A spring 18 (Pig. 4) is mounted between the sections 15 and 15" and tends to maintain them separated.

The upper table section is formed with a forward pedestal and a rear pedestal 22. The pedestals 20 and 22 have aligned bearings therein which receive an arbor shaft 24, the arbor shaft being supported between a pair of thrust bearings 25725 in the pedestal 20. The

forward end of the arbor shaft 24 retains an end mill 26 which is to be ground or reground. The arbor shaft 24 is rotatable in the pedestals 20 and 22 but is held in fixed axial position relative thereto by the thrust bearings 25-25.

A collar 27 is mounted on the shaft 24 and has a cam follower or pin 28 projecting inwardly from the inner diameter of the collar and engageable with a helical groove or cam 30 in the shaft 24. The collar has a reduced diameter, as seen at 31, which receives a U-shaped yoke 33 (see Fig. 3), the yoke being adapted to move the collar 27 axially along the arbor shaft 24.

The base of the yoke 33 is formed with a cylindrical pedestal 3S which is received in a similar cylindrical recess in a block 36. The block 36 has a groove 37 which is received over a tongue 38 in a transversely movable block 40. The block 40 has a groove 42 (Fig. 3) extending at right angles to the tongue 38. The groove 42 receives a tongue 45 on an adjusting block 47. The block 47 is pivotally connected to the upper plate 15l of the table 15 by a pivotal screw 47 and may be clamped in adjusted position by set screws 48-43 operating in arcuate T slots 43. The block 40 is circular in cross-section and is received in a circular opening in a square collar 49. The-collar 49 is restrained from moving 1ongitudinally relative to the base 10 by rails Sil-50 but is free to move transversely along the rails Sil-50. The

rails are supported by posts 51-51 carried on the top of the base 1t) and secured thereto by bolts 52-52, or equivalent fastening means.

Since the rails prevent movement of the block 40 axially of the arbor shaft 24 while permitting its movement transversely thereof it follows that as long as the tongue 45 is parallel to the arbor shaft 24 there will be no relative movement between the base 10 and the yoke 33, and therefore as the table 15 slides, the pin 28 will remain stationary relative to the base 10 as the arbor shaft 24 moves, causing the arbor shaft 24 to turn with the groove 30.

Similarly, foreach angular setting of the block 47 according to a scale S the block 40 is moved a definite distance either to the right or left of the axis of the machine. Any movement of the block 40 to the right or left causes a relative movement of the block 36, effecting a change in the distance the yoke moves, and hence causes a change of pitch on the arbor shaft 24. Thus the true pitch may be marked on the scale S.

T he yoke 33 has a bracket 53 formed on its upper end, the bracket 53 forming a support for a motor 55. The motor 55 has a gear 57 lixed on its shaft, the gear 57 driving a second gear 58. The gear 58 is mounted on the arbor shaft 24 and is fixed to the collar 27 to rotate the arbor shaft constantly during the grinding operation.

The gear 58 is fixed to a sleeve 6) which is received on the arbor shaft 24 and extends through the bearing in the pedestal 22. The sleeve 60 receives a cam 64 which has a number of nodes or high points thereon (Fig. 4) which correspond in number to the number of cutter edges on the end mill 26. The cam 64 may be adjusted and fixed circumferentially on the sleeve 60 so that the nodes 65 occur opposite cam followers 67 as the cutting edges of the end mill pass the grinding wheel 68.

The cam follower 67 is mounted for both rotational and yaxial movement on a shaft 69 so that the cam follower 67 Kcan follow the axial movement `of the cam 64. The cam follower 67 has radially extending flanges 70 which envelop the sides of the cam 64 to insure constant contact between the cam and follower.

The shaft 69 is carried in a stand-ard 72 formed on the lower plate 15 of the table 15 so that contact of the high point or node 65 of the cam '64 by the follower 67 compresses the spring 18 and moves the end mill 26 into engagement with the grinder 68.

- The grinder 68 may form an integral part of the present apparatus Vin which casel it isjrnounted from the ibase'lt);` or if desired a grinding. wheel of a convenient surfaceY grinder may be utilized.

` peraton In operation, the end. mill 26 which is to be ground or sharpened is placed in the end of the arbor shaft 24 and secured thereinxas by a machine screw 75.

YThe scale S yon the block 47 may then be set for the correct pitch of the cutter edges.

' The gear 58, being 'connectedV to the collar, 27, rotates the collar 27 which in turn rotates the shaft 24' through Vthe pin 28. Y

Simultaneously, the gear 58 rotates the sleeve 60 which*` in turn rotates the cam 64. The cam 64 acts Iagainst the cam follower 67 to force the end mill 26 against the grinding wheel68 as each cutting edge of the end mill 26 passes the grindingwheel 68.

The sliding tableV may Vthen be reciprocated longitudinally on the base 10. As thev table 15 slides back and forth, the rails 50 4act against the collar 49 to prevent longitudinal Vmovement of the sliding block 40, but permi-tV transverse movement of the block in response to the angle Y at which the adjusting block 47 is set.

The transverse movement of the block 40 causes a t longitudinal movement lof the block 36 which in turn movesthe pin 28 longitudinally in the, slot 30 to vary the posit-ion of the pin 28 in the slot and ythus effect rotation of the shaft 24 independently of the motor 55. This independent rotation of the shaft 24 is regulated by setting of the adjusting block 47 to the pitch of the particular end mill 26 being ground, so that the cam 64 always acts Vto advance the mill onto the grinding wheel in position to grind the cutting edge of the mill.

It will be realized that the hereinbeforedescribed form` of the invention isl givenY merely asV apreferred example thereof and that various changes in size, shapeV and arrangement of parts may be made without departing from the spirit of the invention .or theV scope of the subjoined claims.

That which is claimed as new and is desired. to -be secured by United States Letters :Patent is:

l. In a tool grinder, a base, a grinding lwheel mounted on said base to grind a tool having cutting edges, a table slidable longitudinally on said base, a pair of spaced pedestals carried by said table, an arbor shaft rotatably mounted between said pedestals, said shaft having a helical jcam'. cut therein, a collar mounted on said shaft to reciprocate axially thereon, a cam follower mounted in said' collar and' projecting inwardly into engagement with said cam, means to rotate said collar to drive said shaft through said follower, means on said table co-operating with means on lsaid base to vary. the axial motion of the collar Ias the table reciprocates. to rotate the coll-ar relative to the arbor shaft to vary the rotation of the shaft asY the A cam l64 having` the. same number, of nodes 65- as there are cutting edges'on\ latter rotates, and means to move the tool against the grinding wheel to grind the cutting edges of the tool.

2. In a tool grinder, a base, a table mounted for reciprocating movement on said base, a pair of spaced pedestals formed on said table, an arbor shaft having a fixed axial position relative to said table and rotatably mounted between said pedestals and adapted to secure a tool to be ground, said arbor shaft having a helicalV cam therein, a collar mounted about said shaft, a cam follower projecting inwardly from said collar and into engagement with said cam, a gear fixed concentrically on said collar to drive the shaft through said follower, a motor mounted adjacent said collar, a gear carried by said motor and in engagement with said first named gear, a yoke supporting said motor and engaging said collar to move the collar longitudinally and eiect movement of the follower in the camto vary the rotation of the arbor shaft independently of they motor as the table is'reciprocated on thebase, and means on said'basercooperating with means on said' table to vary the longitudinal travel ofthe yoke Vto cause the shaft to'rotate independently of said motor in conformance with the pitch of the tool being ground.

3. In a tool grinder, a base, La table mounted for reciprocating movement on saidbase, a pair of spaced pedestals formed on said table, an arbor shaft having a fixed axial position relative to said table and rotatably mountedhe- ,tween'said pedestals and adapted to receive a tool to be "ground,l said arbor shaft having, a helical cam. therein,

afcollar mounted about said shaft Yand axially movable thereon, a cam follower projecting inwardly from said collarand into engagement with said cam, a gear xed V-concentrically on said collar Vto drive the shaft through said follower,I a motor mounted adjacent said collar, a

gear carried by said motor and in engagement Vwith said first Vnamed geana yokesupporting said motor and engaging said collar, to move. the collar longitudinally rela- Y Y tive to said arbor shaft and effect movement of the follower in the cam to, vary the rotation of the arbor shaft independently.v of said-motor as 'thel table reciprocates, and means, including an element having pure longitudinal movement engageable with an element havingpure'transverse movement, to` vary the longitudinal travel of the yoke to cause thev shaft to rotate independently of said motor in conformance with the pitch ofthe tool being ground. l y Y 4. In a grinder, a base, a table slidably ymounted on said base, Aan arbor shaft including meansto receive a multiedged tool having helical cutting edges inl one end thereof, said arbor shaft being mounted to reciprocateV with said table on said base, means to eiect continuous rotation of the shaft, a rotating grinding wheel mounted Yadjacent one end'of `the arbor shaft, meansl engaging the arbor shaft to vary the rotation thereof in accordance with the axial reciprocation of the shaft, and means to move the arbor shaft toward and away from said grinding wheel periodically duringthe grinding.

References `Cited in the tile of this patent UNITED STATES PATENTS 

